1. Field of the Invention
The present invention relates to a refrigerator, and more particularly, to a method for controlling an operation of a refrigerator with two evaporators.
2. Discussion of the Related Art
Generally, a refrigerator is an appliance used for fresh storage of food for a prolonged time period, and a recent trend has been a development of a refrigerator for effective storage of Kimchi, a Korean specialty.
Referring to FIG. 1A, the refrigerator is provided with a body 10, a freezing chamber 20 for frozen storage of food, a refrigerating chamber 30 for cold storage of food, and a refrigerating cycle for cooling the freezing chamber and the refrigerating chamber. The unexplained reference symbols 40 and 50 are a fermenting heater operative in a fermenting mode, and a damper, respectively.
Referring to FIG. 1B, the refrigerating cycle is provided with a compressor 1 for compressing refrigerant, a condenser 2 for isobaric condensing of the compressed refrigerant, a capillary tube 3 for adiabatic expansion of the condensed refrigerant, evaporators for the refrigerating chamber and for the freezing chamber 4 and 5, respectively, provided at the refrigerating chamber 30 and the freezing chamber 20, respectively for isobaric evaporation of the expanded refrigerant.
The refrigerating cycle is also provided with a three-way valve 6 at a branched point of a flow passage for selective introduction of the refrigerant condensed at the condenser 2 into the evaporators for the refrigerating chamber 4 or the freezing chamber 5 along the branched flow passage, a condenser fan 2a at the condenser 2 for cooling the condenser or the compressor 1, a refrigerating chamber evaporator fan 4a at the refrigerating chamber evaporator 4 for accelerating heat exchange by forcible circulation of air heat-exchanged at the refrigerating chamber evaporator 4, and a freezing chamber evaporator fan 5a at the freezing chamber evaporator 5 for accelerating heat exchange by forcible circulation of air heat-exchanged at the freezing chamber evaporator 5.
Hereinafter, referring to FIG. 1B, the operation of the refrigerator having the refrigerating cycle will be explained.
First, in Refrigerating-Freezing (RF) cycle operation, in which both the refrigerating chamber evaporator 4 and the freezing chamber evaporator 5 are operative, the three-way valve 6 is opened to introduce the refrigerant into the refrigerating chamber evaporator 4, and the gaseous refrigerant compressed at the compressor 1 undergoes a phase conversion into a liquid refrigerant as it passes through the condenser 2, a pressure drop as the refrigerant passes through the capillary tube 3, a phase conversion into gaseous refrigerant as it passes through the refrigerating chamber evaporator 4 and the freezing chamber evaporator 5 sequentially, conducting a heat exchange with air in the refrigerating chamber 30 and the freezing chamber 20, respectively, and is then introduced into the compressor 1.
Second, in Freezing (F) cycle operation in which only the freezing chamber evaporator 5 is operative, the three-way valve 6 is opened to introduce the refrigerant into the freezing chamber evaporator 5, and the gaseous refrigerant compressed in the compressor 1 is involved in a phase conversion into liquid refrigerant as it passes through the condenser, a pressure drops as it passes through the capillary tube 3, and a phase conversion into gaseous refrigerant as it passes through the freezing chamber evaporator 5, conducting a heat exchange with air in the freezing chamber 20, and introduced into the compressor 1.
In the meantime, referring to FIG. 2, in a related art refrigerator, a Freezing (F) control is employed in which the compressor 1 is turned on/off according to a temperature of the freezing chamber 20. That is, if the freezing chamber 20 temperature exceeds an upper limit of a preset temperature range, the compressor 1 is put into operation, to start the RF cycle operation or the F cycle operation, and if the freezing chamber temperature is within the preset temperature range, the compressor 1 is stopped, to stop the RF cycle operation or the F cycle operation.
However, the foregoing related art method for controlling operation of a refrigerator has the following problems.
First, the stop of the compressor 1 under the F control method has the following problem. If the compressor 1 is stopped in the middle of the F cycle operation because the freezing chamber 20 temperature is within the preset temperature range in accordance with the F control method as discussed, but the refrigerating chamber 30 temperature exceeds an upper limit of the preset temperature range due to internal and external loads during a time period from when the time the RF cycle operation is stopped to a time the compressor 1 comes into operation again, there is a problem with the cold storage of food.
That is, if the RF cycle operation is stopped as the refrigerating chamber 30 temperature is within the preset temperature range, the compressor 1 is stopped, and the F cycle operation is stopped too as the freezing chamber 20 temperature is within the preset temperature range. In this instance, if an external air temperature is high above a designed value due to abnormal high temperature due to weather, there is an excessive heat exchange between external air and internal air of the freezing chamber 20 and the refrigerating chamber 30, causing a temperature rise of the refrigerating chamber 30 from a point in time when the RF cycle operation is stopped. This increase in temperature occurs at a rate higher than in the freezing chamber 20, as a surface area of the refrigerating chamber is larger than that of the freezing chamber 20, and an insulation thickness of the refrigerating chamber is thinner than that of the freezing chamber 20.
Eventually, because the refrigerating chamber 30 is in a state in which the temperature thereof exceeds the preset temperature range from a time point in time when the RF cycle operation is stopped to a point in time point when the RF cycle operation is started again as the compressor 1 is put into operation again, there is a problem with the cold storage of food.
Also, since the compressor is stopped if the freezing chamber 20 temperature is within the preset temperature range, when hot food is put in the refrigerating chamber 30 after the F cycle operation is stopped, the refrigerating chamber 30 temperature exceeds the upper limit of the preset temperature range.
According to this, since the refrigerating chamber 30 temperature exceeds the upper limit of the preset temperature range from a moment when hot food is put in the refrigerating chamber 30 to a moment when the RF cycle operation starts again by putting the compressor 1 into operation again, there is a problem in the cold storage of food.
Second, if the compressor 1 starts under the F control method, the following problem is caused.
If operation of the compressor 1 is determined only by the freezing chamber 20 temperature, that is, if the compressor 1 is put into operation only when the freezing chamber 20 temperature exceeds the upper limit of the preset temperature range, there is a problem with cold storage of food when the refrigerating chamber 30 temperature exceeds the upper limit of the preset temperature range due to said the foregoing various factors (the external air temperature, or hot food temperature) or frequent opening/closing of the refrigerating chamber 30.